The present invention relates to attitude and position control of satellites which are equipped with solar generators and/or solar sails.
It has been suggested to control the attitude of satellites under utilization of the so-called spin effect in that, for example, the satellite is associated with a reaction (inertia) wheel which, in dependence upon the attitude and position of the satellite is changed as to its rotational speed to control particularly the attitude. A typical attitude cantrol system is for example disclosed in U.S. Pat. No. 4,023,752. Satellites which are to be controlled are oriented with respect to the earth, and are in a position which could be described as geostationary. They are usually placed into the proper attitude after having attained their respective orbit. Reorientation of the satellite is carried out in a known manner through thrust producing systems.
Solar wind, or solar pressure, is available as a source of solar energy which is effective upon a satellite, and is capable of causing an undesired change in the satellite's attitude. Thus, onboard sensors are required to monitor this effect and to initiate restabilization of the attitude of the satellite. On the other hand, it has been proposed to use this so-called solar sailing effect, i.e., the solar wind, as a source of energy, by means of which a particular attitude of a satellite can be attained. Thus, for example, in combination with a spinning wheel, solar sails can be turned for purposes of restabilization. It will be appreciated that an attitude control in but two axes is possible in this manner.
If a satellite is placed into orbit, the solar generator of any kind, including a solar cell array or solar sails, are folded, rolled up, or in any manner compactly stored during the launching procedure, and these devices are deployed after the satellite has attained its orbit.